What are the opensource ide/editors for Java?

Question

Java

I rummaged through a bunch of projects on github using the keywords java ide / editor - everything is not right.
Any simple editor with plugin support will do, something like linting would be nice. I want to see how it works from the inside.
Preferably something simple.

Answer 1

BlueJ
Sources there

Answer 2

idea community for collection

Answer 3

Eclipse

Answer 4

Arduino IDE

Answer 5

forgot to mention netbeans

Answer 6

VSCode, so-and-so